Ventilation system



Feb. 7, 1950 B. E. DEL MAR 2,496,862

VENTILATION SYSTEM Filed July 15 1946 IN VEN TOR.

Patented Feb. 7, 1950 VENTILATION SYSTEM Bruce E. Del Mar, Los Angeles',Calif., assignor to Douglas Aircraft Company, Inc., SantaMonica,

Calif. 7

Application July 15, 1946, Serial No. 683,805

1 This invention relates to a ventilation system and more particularlyto such a system for pressurized aircraft cabins. V

In control systems for pressurized aircraft cabins heretofore proposedone or more air delivering means such as superchargers have been used tosupply ambient air to the cabin under a pressure greater than ambientflight pressure. 'Although such systems with varying success regulatedthe absolute pressure of the air within the cabin, considerabledifficulty has been experimood in maintaining and regulating thehumidity of the cabin air, particularly in flight operations where theambient air supplied to the cabin had to be heated prior to itsintroduction into the cabin. As should be understood, the heating of theair reduces the relative humidity of the air and if the same is nothumidified the air becomes uncomfortably dry and must be held at ahigher temperature for the comfort of the passengers. In the system ofthe present invention air is supplied to the cabin by a plurality ofsuperchargers. The pressure of the air within the cabin may becontrolled by any regulatory means desired for varying the-rate of airdischarge from said cabin relative to the rate of air delive'ry to saidcabin. The temperature of the'cabin air can be regulated by heating andcooling means 5 Claims. (C1. 98 --1.5)

of any type desired through which'the air is passed prior to itsintroduction into the cabin.

It is possible to maintain the air at a comfortable relative humidityduring those flight operations which require that the temperatureof' theambient air be raised prior to its introduction into the cabin, byrecirculating a part of the cabin air. The air recirculated will, ofcourse, be warm and need not be heated prior to its reentry into thecabin and, consequently, the. humidity of this air remains substantiallyconstant. This can be accomplished by a fan or blower for circulatingthe air through a duct supplied with suitable filters for deodorizingthe air recirculated and for removing impurities from the air. The fanor blower and the means for operating the same increase the'grossweightof the aircraft, which is ob'jectionablefor it reduces the loadcapacity of the aircraft.

The present invention providesa recirculation system which utilizes oneof the superchargers required to pressurize the cabin for recirculatingthe air and thus eliminates the use of a separate fan or blower and themeans for operating the same. A further saving in weightof the equip-.ment necessary to recirculate the air is possible,

for the cabin air inlet duct can alsob'e' used as a.

part of the recirculation duct system. The recirculation duct systemincludes a duct leading from the cabin to the inlet of the onesupercharger, and passage of air through this duct is controlled by avalve system which is so formed that the supercharger inlet is closedwhen air is being drawn from the cabin.

- The duct leading from the cabin to the supercharge inlet is furnishedwith suitable filtering units for deodorizing and filtering the airrecirculated. The filtering units are preferably mounted so that thesame are easily accessible tothe end that they can be quickly removedfor servicing. As the filtering units are accessible they can be easilyremoved if flights are to be made under weather conditions which willnot require that the incoming air be heated to any large extent prior toits introduction into the cabin. This feature permits a weight savinghighly desirable in commercial airline operation. As only the onesupercharger is used as a recirculating fan or blower, suflicientamounts of fresh air are supplied to the cabin by the othersuperchargers to maintain the air wholesome within the cabin. Otherfeatures and advantages of the present invention will be apparent fromthe following description of the invention taken in connection with theaccompanying drawing in which the figure is a diagrammatic view of anaircraft cabin showing my ventilation system. I

The system of the present invention, referring. now to the drawing, isshown in connection with a sealed aircraft cabin l0. Air is directedinto the cabin through air ducts II and 12 arranged to deliver a flow ofair to the cabin from supercharging blowers I 3 and I 4 respectively.The blowers, as will be under-stood, are required to force air into thecabin to maintain the absolute pressure of the cabin air in excess ofambient air pressure during flights of th aircraft at relatively highaltitudes.

' The blowers are arranged to be supplied with air from ram ducts l5 andare driven through shafts i6 by speed control prime mover-s I! in such amanner that a substantially constant rate of air flow is suppliedthrough the ducts II and 12 to the cabin l0.

-'-- Air from the ducts I I and I2 is led into the cabin through aninlet duct it formed with a plurality of discharge conduits l9 locatedat spaced points in the aircraft cabin. Mounted in the inlet duct i8 isa temperature regulating mean-s diagrammatically shown at 2| which maybe of the type described and claimed in my coof the cabin H] which isadapted to be closed or variably restricted by a suitable valve 24 con-:trolled by some pressure responsive controlsys:

tem diagrammatically illustrated at 25'. Asthe" rate of air delivery issubstantially-constant:cahinzls absolute pressure can be increasedbyrestricting-F1.)

or closing the opening and decreased by opening the same. The dischargeopening 23 is prefers ably located on the cabin wall in a region wherethe pressure along the wall is, due to surface-nit: velocities, slightlyless than that of the ambient atmosphere Asthe supercharging blowers .I3and. I4 sup,- plyvthe' -cabin:;with ambient air for. pressurizing thecabinuthe-air ,obviously will have to be heated before: its passag intothe cabin during cold weather operations and wherethe aircraft is: be-:ing flown at altitudes at which the' air is relae tivelycold. Theheating of 'the'air will obviously reduce the relative humidity of theincoming air,

andrthe: air: conditionin means 2| preferably includes some .means iforhumidifying-the :heated air; This requires-a supply of Water tobe-introduced into; the s; incoming air "stream, and, 'this water:supplywhere the'aircraft is-to beifiown relatively long.distances-mustbe a relatively large one.

To-reduce=theamount ofwater whichmust he carriedifor 'humidiiyingtheairvsupplied to the cabin? during roperations. in cold air; the presentinvention:- provides::: means; for recirculating; at :40

least a; part of ithe 'ain supplied to the cabin. As should beunderstood. this will aid-maintainingthe relative humidity of: the airin the cabin. for the air. recirculated willlibewwarm .andnneed-enot beheated prior; to: its 7 reintroduction into the cabin; In: other words,while-the amount of. air furnished ltorthe cabin-As maintained constant.only one-half. as much:heatediambient air, which is very dry; need; be:introduced into the-cabln during :these conditions;

The air is recirculated, in the now-preferred embodiment :oftthe r;present invention. by providing a duct ifi-zleadingfrom asuitableregister 21- in:the cabin-l 0 .to the ramiinlet. l 5 of thesuper?charging blower l3. are mountedrrwithin'the:duct'26-for the purpose ofdeodorizing rand" fi1tering:the air withdrawn from the :cabin: before itisagain" introduced into the same.

The .filter units preferably comprise a dust re- 60 moving. unit" 28 andone containing activated charcoal here shown at 29.; Theidust filter 28should be locatedirbetween .the cabin and :the tieodorizingiunitl 29*;topreventrthe charcoal-vfrom becoming-fouledrwith dust and other foreign.65

particles in;the cabin-air.

The, filtemunitsgarepreferably-mounted with; in the cabin for easyremoval to :facilitate clean:- ing and maintenance ofthefiltersand-also.to

permit their:removal from-:the aircraft ifqthe .70

same. .to be .flown -under- "weather; conditions in rwhichytheairris notheated to any largezex-v -tent before itissunplied to thecabin.

To ",permitltthe :airrto be withdrawn :from; the

cabin:- through; the. duct 26.x: a; valve .30 155.5016

A pluralityof filter; units 5 mounted that it can be used to selectivelyclose the ram inlet [5 of the blower l3 and open the duct 26 to thepassage of air when flight conditions necessitate recirculation of theair. It will be seen that the valve is movable between alternatepositions in which either the inlet 15 or the duct 28 is closed to thepassage of air.

Although-any7means adesiredmay be used to control: thei-position ofthevalve" 30, to simplify the illustration of the invention this meansis shown as a cable and pulley system 3| adapted to. beoperated by ahand lever 32 located in the pilot's compartment of the aircraft. Asshould beaunderstood; operation of the hand lever 32 :fwill'ieithercloserethe ram inlet 15 and open the duct 26 or closethe duct 26 andopen the ram inletJS depending upon the direction of movement of thehand lever 32.

Thesuse of one of th supercharging blowers required for pressurizing thecabin to recirculate apart ofithebabin air. obviates the 115801asseparate circulating f anror blower and: a power. means for operatingthe same andnthusxelirninates-the weight Ofijhis. equipment.

The-recirculatingduct 26 does not greatly add to the :gross weight. or:the 1 aircraft, as this duct can be-made very;-small.:eventhough thepressure-edropgthrough-athis -.duct rmaygbe very large. This. ispossible. because ,when the supercharger =l3':is;zused torecirculaterthe air;the latter. has

an; abundance-sot power; andcthe heating assoe ciatedryvith ahigh ductpressureloss will; not be importantisince theiconditionssof use of therecirculation;system involvesheating of the cabin considerablyyabove thtemperature of the am bient air.

Although:the;;now preferred embodiment of the-inventiomhasbeenshownranddescribed herein; it is, to -beeunderstoodethat theinvention is notwto-wbeelimlted utheretoi-fortthe invention issusceptible e vchangesinform] and detail. within the-scope oftheappendedclaims.

I claim-:-

1.; A -.ventilatinnnsystem:forran. aircraft cabin comprisingrizzasplurality -ofz'means for delivering ambient vair 'itOsaidicabin:undern:pressure higher thanramblentflight.pressureafonpressurizing the same; ductmeansleadingfrom theoutlet of each air-delivering means; andrwalve means operabletQTClOSQeSflId inietrso that airbcanxbe withdrawn fromrsaidmahinzby said.onezairdelivering means andodelivened-jtherebya-to said-xcabin wherebyat least a part of the. airJWithin-said'cabin can be recirculatedi 2.;Aventilation systemrfor-an-aircraft cabin comprising :a aplurality 'ofsuperchargers for deliveringambient air to said rcabin for pressurizingthesame; an; inlet duct'leading to saidcabin: duct means leading fromthe outlet of each supercharger.- torsaidrinletduct;::duct means leadingfromthe 'cabinzto 'the, inlet "of; one of said super-i chargers:valveemeans operableto .close said in; let'so -that tan:canzbeawithdrawni from said cabin by;:saidnonesuperchargerrandidelivered thereby to said cabin whereby at least "a2partof :theair within: said -cabinzcam be recirculated and filtermanna-mounted .in the r duct: means leading from 'saidrcabinzto the onesupercharger."

3.- Awentilationesystemvfor an aircraft :cabin comprlsingg :a epluralityof..-means for. delivering ambient-:atnstozsaidcabin:-,.for.;pressurizingi;the same; ,anzinletrductileadlnzato:saidcabin; duct livering means to said inlet duct; heating means in saidinlet duct for heating air therein; duct means leading from the cabin tothe inlet of one of said air delivering means; valve means for closingsaid last named duct means; means Within said cabin for operating saidvalve means to close the inlet of said air delivering means and opensaid duct means leading to said inlet whereby said air delivering meanscan be used to recirculate at least a part of the air within said cabin;and a plurality of filter units arranged in said duct means leading fromthe cabin to the one air delivering means for cleaning and deodorizingthe air withdrawn from the cabin.

4. A ventilation system for an aircraft cabin, comprising-J: a pluralityof means for delivering ambient air under a pressure higher than ambientpressure to said cabin for pressurizing the same; duct means leadingfrom the cabin to the inlet of one of said air delivering means; valvemeans disposed at the intersection of said last named duct means and theinlet for ambient air of said one air delivering means and movablebetween alternate positions, said valve means in one of said positionsclosing said inlet and opening said duct means and in the other of saidpositions closing said duct means and opening said inlet means; andmeans within said cabin for moving said valve means to and from saidalternate positions whereby said valve means may be moved to theposition in which the same closes said inlet and opens said duct meansso that said air delivering means can be used to recirculate at least apart of the air furnished to said cabin.

5, A ventilation system for an aircraft cabin, comprising: a pluralityof means for delivering ambient air under a pressure higher than ambientpressure to said cabin for pressurizing same; duct means leading fromthe cabin to the inlet of one of said air delivering means; valve means,movable to alternate positions, so disposed and organized with referenceto said duct means and to said inlet as, in one of said alternatepositions, to close said inlet and open said duct means and, in theother of said alternate positions, to close said duct means and opensaid inlet; and means within said cabin operable to efiect movement ofsaid valve means to and from said alternate positions whereby saiddelivering'means may be employed either as a supercharger to charge thecabin from the ambient atmosphere or as a fan to recirculate at least apart of the cabin air back thereinto.

BRUCE E. DEL MAR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,985,050 Merle Dec. 18, 19342,002,057 Gregg May 21, 1935 2,109,512 Stacey, Jr Mar. 1, 1938 2,119,402Puller May 31, 1938 2,303,334 Dauphinee Dec. 1, 1942 2,328,489 Pfau Aug.31, 1943 2,439,793 Braddon Apr. 20, 1948 2,444,951 Paget July 13, 1948

